I had a little bit of free time today so I thought I'd start installing my DJ kit. I pulled the slide and spring and got the stock spring and the DJ spring confused. Does anyone know off hand which is which? One has .022" wire with more coils and the ends aren't closed neatly. The other has less coils and .025" wire with neatly closed ends. I originally thought the .022" spring was the DJ spring that came in the kit, but now I'm not sure.

 

I did an unscientific test by compressing both springs against a small digital postal scale that I have. The spring with the lighter gauge wire (I measured it again and it's more like .023-.024") was about a half ounce lighter fully compressed than the the heavier gauge spring. So I guess I should be using the spring with less compression force?

 

I think that's correct.

 

Slide spring from my Moose Racing/DJ kit #2152

 

That looks exactly like the heavier gauge spring. Now I'm confused. The ends are nicely closed on yours. I'll try and get pics of mine side by side later this evening when I get home.
thanks!

 

I had a little extra time this morning so here's pic of the two springs...the lighter gauge spring is on the bottom. I just measured the wire with my digital mitutoyo calipers and it's .0225" the top one measures .024". Not much difference in the two. Has anyone tried cutting off a coil or two? Let me see if I can get this straight on what these springs do: As the throttle butterfly is opened, the engine pulls in more air and creates a vacuum on the top of the diaphragm effectively raising the needle jet against the force of the spring compressing. A lighter spring would give a quicker throttle response, correct?

 

I thought the DJ spring was the shorter...let me find my kit and measure.

 

In your picture the DJ spring is on top.

 

Yes. And quicker response when closing as well.

And if you are trying to measure spring rate it should generally not be fully compressed, but over some given distance (e.g. ounces per inch).

 

Some additional thoughts on obtaining quicker throttle response:


Everything I've heard if you cut a spring it increases its rate. What happens to a spring's rate if you cut a few coils off, then stretch the spring out to original length? Is the spring rate reduced? If the rate is entirely dependent on the wire gauge etc, then it may not change. Something to try with a hardware store spring first I suppose..

If you want to effectively lighten the slide, the "wings" on each side of the round part of the slide that fit into the slots in the carb body are ripe for weight reduction aren't they?




I don't think they help to seal off the upper slide area etc, so drilling some holes into them, or grinding half round reliefs in their side should be okay.

All they do is orient and guide the slide as it moves up and down. (I think..)


If you chamfer this section of your CVK air will be able to go in quicker and push the slide up faster. I went back with my Dremel sometime after this photo was taken and opened the slot up a little more; cleaning it up in the process.




Also, if you were to add something like round Delrin rod to the top center of the carb cap; pointing down through the center of the spring, it would reduce the volume above the slide. Reduced volume should let the slide react faster as its upper cavity "empties out" quicker therefore letting atmospheric pressure push the underside up faster.

That pronged spring locater inside the carb cap is just held in by a rivet in the center. I'd already added Delrin rod to mine, but then opted for the 36mm and haven't really done any more work on the 34.